Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Celtor Chemical Works
EPA #: CAD980638860
Congressional District: 01
Other Names: Hoopa Valley Indian Reservation
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 12/30/82
Final Date: 09/08/83
Deleted Date: 09/30/03
The 13-acre Celtor Chemical Works site, located in the center of the Hoopa Valley Indian Reservation, was formerly an ore milling and concentrating facility that processed sulfide ore for copper, zinc, and precious metal extraction. The site owner leased the site from the Hoopa Valley Indian Tribe from 1958 until 1962. During this time, sulfide ore from the nearby Copper Bluff Mine was processed and wastes dumped around the mill area and slurred into the Trinity River and onto a gravel bar next to the River. Celtor Chemical Corporation abandoned the site and mine waste generated from the operations were left on site. These tailings, along with non-specific releases of processed ore, were the cause of acidic surface water runoff and elevated metals concentrations in the soils throughout the site. The site consisted of the plant, an adjacent pasture used for grazing livestock, a gully connecting the plant and the Trinity River, and a fishing access road that is frequently used by local residents. Since the mine was shut down and previous EPA remediation completed, significant river sediment has buried most of the area where waste remnants may be located in the lower portion of the site. After Superfund site cleanup was completed and the site deleted from the superfund list, additional tailings waste has been discovered next to the Trinity River and the original mill area shows signs of zinc-rich salt leaching through the cap placed over the former mill. This 2016 discovery has triggered the initiation of a supplemental Remedial Investigation. Approximately 200 people lived within one mile of the site. The Trinity River, which supports the only fish resources for the Hoopa Indians, flows through the center of the reservation and along the north edge of the site.
Contaminants and Risks
- Soil and Sludges
Soil was contaminated with heavy metals including arsenic, copper, lead, cadmium, and zinc. Potential health threats to people included accidental ingestion or dermal contact..
Immediate Actions: In 1983, the EPA conducted a focused feasibility study. After a public comment period, EPA signed a Record of Decision on October 4, 1983 to conduct a time critical removal action. By December, 1983, EPA had excavated 1400 cubic yards of visibly contaminated materials. This material included tailings, non-concrete structures, and a portion of the pasture adjacent to the site. The main portion of the site was fenced, and the access road was covered with gravel. The flow of several springs was diverted away from the contaminated areas and into a nearby creek, which emptied into the Trinity River. During this cleanup action, additional contamination was discovered in locations not previously identified, so EPA conducted a more detailed investigation.
Entire Site: On September 30, 1985, EPA signed a Record of Decision that selected a more complete remedy to clean up the Celtor Chemical Works site. From October 1987 to the final off-site shipment in October 1988, the EPA excavated an additional 1,200 cubic yards of contaminated material from the site and disposed of them off site at an EPA-approved hazardous waste disposal facility. Backfilling, contouring of the land and revegetation activities were also completed in 1988 followed by a one-year post remedial maintenance period.
To ensure that cleanup actions remained protective of human health and the environment, EPA conducted five-year reviews published on September 30, 1993 and August 29, 2001. To resolve some uncertainties identified in the review and address community concerns, EPA took samples of site soils in May, 2003. A total of 38 soil samples and five surface water samples were taken to ensure that no contaminants of concern remained on the site above cleanup goals. Sample results confirmed that the site was free of contaminants above cleanup goals. Therefore, EPA concluded that the soils do not pose an unacceptable health hazard for residential or unrestricted land use. In 2006, EPA scientists formally certified that the entire site achieved Unrestricted Use and Unlimited Exposure (UU/UE).
In August, 2016 a site visit by EPA discovered tailings exposed in the gravel bar of the Trinity River that had elevated arsenic, copper lead, zinc and other constituents. A site investigation to determine the nature and extent of these tailings as well as the mill area was initiated in July of 2017.
Cleanup Results to Date
The site was deleted from the NPL on September 30, 2003. Because of the discovery of additional waste material, a remedial investigation supplement has been initiated. The site may no longer meets the criteria for Unrestricted Use and Unlimited Exposure (UU/UE) as previously determined pending the results of the investigation.
Potentially Responsible Parties
Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.
Documents and Reports
Public Information Repositories
The public information repositories for the site are at the following locations:
EPA Site Manager
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
12 Cannery Row
Hoopa Ca 95546
After Hours (Emergency Response)